Hi Vlad, From: Vlad Olariu <florinvlad.ola...@gmail.com<mailto:florinvlad.ola...@gmail.com>> Date: Saturday, June 6, 2015 at 1:40 PM To: OSPF WG List <ospf@ietf.org<mailto:ospf@ietf.org>> Subject: [OSPF] Cisco OSPF implementation - Different networks on serial links
Hello, I was reading the OSPFv2 RFC, namely, from page 62: The Area ID specified in the header must either: (1) Match the Area ID of the receiving interface. In this case, the packet has been sent over a single hop. Therefore, the packet’s IP source address is required to be on the same network as the receiving interface. This can be verified by comparing the packet’s IP source address to the interface’s IP address, after masking both addresses with the interface mask. This comparison should not be performed on point-to-point networks. On point-to-point networks, the interface addresses of each end of the link are assigned independently, if they are assigned at all. I have tried this on various Cisco routers and it doesn't work. It complains about the interfaces being in a different network. Is this an implementation flaw? This is really a vendor specific question and not a topic for an IETF list. Having said that, Cisco enforces a subnet model for P2P interfaces and advertises the subnet consistent with option 2 in RFC 2328, section 12.4.1.1. You could make the interfaces unnumbered if you want to use addresses in different subnets. Please ping me off-list if you have further questions. Hope this helps, Acee
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